In Wednesday’s New York Times, I wrote about two experimental projects in California to store solar energy produced by photovoltaic rooftop arrays:

In the garage of Peter Rive’s San Francisco home is a battery pack. It is not connected to Mr. Rive’s electric Tesla Roadster sports car, but to the power grid.

The California Public Utilities Commission has awarded $1.8 million to Mr. Rive’s company, SolarCity, a residential photovoltaic panel installer, to research the feasibility of storing electricity generated by rooftop solar arrays in batteries.

As rooftop solar systems provide a growing percentage of electricity to California’s grid, regulators and utilities are increasingly concerned about how to balance the intermittent nature of that power with demand.

One possible solution is to store energy generated by solar arrays in batteries and other systems and then feed that electricity to the grid when, say, a cloudy day results in a drop in power production. And when demand peaks, electricity generated from renewable sources could be dispatched from batteries rather than fossil-fuel burning power plants.

“As soon as distributed solar starts providing 5 to 10 percent of demand, its intermittent nature will need to be addressed,” said Mr. Rive, who is SolarCity’s co-founder and chief operating officer.

SolarCity is teaming with Tesla Motors, the Silicon Valley electric car company run by Mr. Rive’s cousin, Elon Musk, and the University of California, Berkeley, to study how to integrate solar arrays and off-the-shelf Tesla lithium-ion battery backs into the grid. SolarCity plans to put such systems in six homes.

“We think in the years ahead this will be the default way that solar is installed,” Mr. Rive said. “Getting the costs down, though, is not going to be an easy task.”

Homeowners could potentially benefit by tapping batteries at hours when electricity rates are high or using them to provide backup power if the grid goes down.

The research has just begun, and at the moment SolarCity is testing the impact of charging and discharging electricity from the Tesla battery pack in Mr. Rive’s garage. His roof sports a three-kilowatt solar array.

“We’re at the point now where we can direct the battery to charge and discharge at specific times by sending a signal over the Internet,” Mr. Rive said.

Included in the $14.6 million awarded for solar energy storage research by the utilities commission was $1.9 million to SunPower for a project that will store in ice and batteries electricity generated by solar arrays at Target stores.

SunPower, a Silicon Valley solar panel manufacturer and power plant developer, will work with Ice Energy, a Colorado company that makes systems that use electricity when rates are low to form ice. When rates are high, air conditioning refrigerant is cooled by the melting ice rather than by an electricity-hogging compressor.

The Ice Bear system and a solar array will be installed at one Target store while battery packs will be used at two other stores in California.

photo: Todd Woody

In a story I wrote with Clifford Krauss in Monday’s New York Times, I look at how the San Francisco Bay Area has is scrambling to prepare for the arrival of mass-market electric cars later this year:

SAN FRANCISCO — If electric cars have any future in the United States, this may be the city where they arrive first.

The San Francisco building code will soon be revised to require that new structures be wired for car chargers. Across the street from City Hall, some drivers are already plugging converted hybrids into a row of charging stations.

In nearby Silicon Valley, companies are ordering workplace charging stations in the belief that their employees will be first in line when electric cars begin arriving in showrooms. And at the headquarters of Pacific Gas and Electric, utility executives are preparing “heat maps” of neighborhoods that they fear may overload the power grid in their exuberance for electric cars.

“There is a huge momentum here,” said Andrew Tang, an executive at P.G.& E.

As automakers prepare to introduce the first mass-market electric cars late this year, it is increasingly evident that the cars will get their most serious tryout in just a handful of places. In cities like San Francisco, Portland, Ore., and San Diego, a combination of green consciousness and enthusiasm for new technology seems to be stirring public interest in the cars.

The first wave of electric car buying is expected to begin around December, when Nissan introduces the Leaf, a five-passenger electric car that will have a range of 100 miles on a fully charged battery and be priced for middle-class families.

Several thousand Leafs made in Japan will be delivered to metropolitan areas in California, Arizona, Washington state, Oregon and Tennessee. Around the same time, General Motors will introduce the Chevrolet Volt, a vehicle able to go 40 miles on electricity before its small gasoline engine kicks in.

“This is the game-changer for our industry,” said Carlos Ghosn, Nissan’s president and chief executive. He predicted that 10 percent of the cars sold would be electric vehicles by 2020.

photo: SolarCity

In my new Green State column on Grist, I write about how SolarCity, a Silicon Valley rooftop solar installer, is getting into the electric-car charging station business:

You can’t get more California greenin’ than this.

Peter Rive can charge up his Tesla Roadster electric sports car in his San Francisco garage with carbon-free electricity supplied by a solar array on his roof. Then, if he’s in the mood for a road trip, he can drive to Los Angeles, stopping at a solar-powered charging station along the way to top off the battery.

The free charging stations on the “solar highway”—aka the 101—were recently installed by SolarCity, the Silicon Valley rooftop solar company Rive founded with his brother Lyndon. (The electric-blue Roadster sitting in his garage was made by his cousin Elon Musk‘s startup, Tesla Motors.)

So what’s a solar company doing installing highway charging stations for six-figure sports cars driven by people with seven-figure salaries?

In part, it’s a result of SolarCity’s connection to Tesla and grants the electric carmaker received from the state of California to demo charging stations. It makes for great PR, of course, but the bigger picture here is how the emerging electric vehicle industry will drive (sorry) the adoption of residential and commercial photovoltaic systems.

photo: Think

Not too many car factories are getting built in the United States these days, especially in the midst of a global economic meltdown. So the prospect of landing Norwegian electric carmaker Think’s North American plant will have Oregon Governor Ted Kulongoski and Senator Ron Wyden turning out Tuesday to take a test drive of the Think City in Portland with company CEO Richard Canny.

Oregon is one of eight states Think is considering for the assembly plant. The company has been coy about identifying those states and has only said that Michigan and Oregon are in the running. About Tuesday’s media event, Think said in a statement that “the future of electric car manufacturing in Oregon will be the topic of a news conference.”

When it comes to electric car factories, there’s a certain Lucy yanking the football away from Charlie Brown risk for prospective hosts. Silicon Valley electric car company Tesla Motors, for instance, so far has signed and then canceled agreements to build a factory for its new Model S sports sedan in New Mexico and San Jose. Los Angeles, the latest factory site, hopes the third time’s a charm.

Nothing nefarious at work here, just the tenuous economics of startup electric car companies. Think, for example, is on the hunt for additional capital so it can restart its assembly plant in Norway. It idled the factory and laid off workers late last year when the credit crunch dried up funding. The company has some heavyweight backers, including General Electric (GE), and marquee venture capital firms Kleiner Perkins Caufield & Byers and Rockport Capital have invested in its North American operation.

Think says it will apply for a low-interest loan from the U.S. Department of Energy under its Advanced Technology Vehicle Manufacturing program to help pay for its U.S. factory. Undoubtedly part of the bake-off with the eight states under consideration is to see which can offer the best tax breaks and incentives.

After the first-year startup phase, the U.S. factory will initially employ 300 workers and is projected to produce 16,000 cars annually, according to Think. Capacity would eventually be expanded to 60,000 cars and a workforce of 900. A research and development center will employ about 70 people.

Green Wombat is betting that Think will try to locate the assembly plant on the West Coast. So far Think has targeted densely populated, environmentally friendly cities — London, Amsterdam — to roll out the Think City, a two-seater urban runabout that goes about 112 miles on a charge. Former CEO Jan-Olaf Willums told Green Wombat last year that the San Francisco Bay Area was a likely gateway market in the U.S. In November, the mayors of San Francisco, San Jose and Oakland inked a deal with Better Place to build a $1 billion electric car charging network in the Bay Area.

Monday night, Green Wombat swung by SF Green, one of a growing number of green tech networking events sprouting up around San Francisco and Silicon Valley. The draw – beyond drinks with a standing-room-only crowd of bright-eyed twenty-and-thirtysomethings in a San Francisco art gallery – was the appearance of leading venture capitalist Ray Lane of Kleiner Perkins Caufield & Byers and Darryl Siry of Tesla Motors, maker of the Roadster electric supercar.

Siry, Tesla’s vp of sales, marketing & service, said five of the $100,000 Roadsters have rolled off the assembly line so far with one car tooling around Los Angeles, and others in the Bay Area and London. By year’s end, Tesla, which has been wrestling with drive train problems, should have more than 100 cars on Bay Area roads, home to many the company’s tech titan customers.

Tesla has raised $145 million, Siry noted, and will do another round before an IPO. The Roadster will always be a limited production marquee car but to mass produce its next vehicle, a five-seat sports sedan code-named White Star, Tesla will need that IPO or project financing. Siry also sketched a future where Tesla might supply electric drive trains to automakers in exchange for project financing.

“Tesla is a tech company wrapped in an automotive brand,” he said at the event co-sponsored by VentureBeat.

Lane and Kleiner Perkins have gone beyond investing in electric car companies to running one. Lane is chairman of Think North America, the U.S. arm of Norwegian electric carmaker Think Global. Kleiner and Rockport Capital took a 50 percent stake in the North American operation, which launched last month.

The Think and Fisker investments are emblematic of a new direction for VCs who have jumped into the green tech game. Unlike the first dot-com era or even the current Web 2.0 age, there’s no quick exit on the horizon for investments in green tech companies that may be years away from producing a product and require hundreds of millions, if not billions, in project financing to build car factories or solar energy power plants.

Lane compared investing in green tech to the long-term horizon needed for investing in biotech startups, where the key is to hit milestones that allow investors to calculate valuations.

Kleiner is also an investor in solar power plant startup Ausra. “Steel prices are killing us,” Lane said. Ausra’s power plants consist of hundred of acres of mirrors mounted on steel frames. “With Ausra, we [calculate] we could deliver solar thermal electricity at 12 cents a kilowatt-hour. But with steel prices, who knows?”

A shortage of qualified green tech workers has become an issue, according to Lane. The nascent solar power plant business relies on recruiting engineers and project developers from the carbon-based industry. “Talented people in project development at companies like Bechtel are maxed out for years on building projects,” he said.

About Green Wombat

Green Wombat is written by
Todd Woody, a veteran environmental journalist based in California who writes for The New York Times, the Los Angeles Times, Grist and Yale e360. He's one of the few people on the planet who have held a northern hairy-nosed wombat in the wild.

Todd formerly was a senior editor at Fortune magazine, an assistant managing editor at Business 2.0 magazine and the business editor of the San Jose Mercury News.